(637g) Experimental Study of the Operating Parameters and Biodegradation Kinetic Model for Wastewater Treatment In a Biological Fluidized Bed Reactor

The effects of the wastewater composition, air supply, reaction temperature and pH on the treatment performance were investigated through systematic experiments in a three-phase biological fluidized bed reactor. Ahead of the experiments, mature biofilms were cultivated on synthetic porous particles made of poly (MA-VAc-MMA). Synthetic wastewater consisting of glucose, NH₃Cl, KH₂PO₄ and modestly additional nutrient salts was applied during the experiments. The results indicated that the initial COD and NH₃-N concentrations as well as the COD/ NH₃-N ratio in the wastewater had an impact on their removals. An optimal removal of COD and NH₃-N was gained with COD of 700 mg/L, NH₃-N of 25 mg/L and the COD/ NH₃-N ratio of 100/4~100/3, respectively. The variations of air flow rate affected both the dissolved oxygen concentration in the reactor and the attachment of the biofilm on carriers, and thus, there existed an optimal air flow rate at which the most effective treatment was achieved. It was also found that the favorable range of temperature and pH for the bio-digestion process were 20~25°C and 6~8, respectively, and beyond which the treatment performance would be obviously inhibited. Meanwhile, semi-continuous experiments were conducted to study the dynamic behavior of COD and NH₃-N removals in the reactor, and the response plots showed that the wastewater contained non-biodegradable components. Hence, based on the Michaelis-Menten equation, a kinetic model considering the non-biodegradable components in the wastewater has been established to describe the biodegradation process of COD and NH₃-N in the reactor. With the experimental plots, the kinetic parameters were estimated using 4th-order Runge-Kutta method combined with simplex method, and the theoretical curve of the kinetic model showed a better fit to the actual response plots than the Michaelis-Menten equation. Thus, it was concluded that the non-biodegradable components in the wastewater have significant effect on the biodegradation process of COD and NH₃-N in the reactor.